Comprehensive, yet simple, stealthy and fast. Datejs has passed all trials and is ready to strike. Datejs doesn’t just parse strings, it slices them cleanly in two.

Less.js is a JavaScript implementation of LESS that’s run by your web browser. As any JavaScript, you include a link to the script in your HTML, and…that’s that. LESS is now going to process LESS code so instead of including a link to a CSS file, you’ll include a link directly to your LESS code. That’s right, no CSS pre-processing, LESS will handle it live.

Simple DOM-less

Johnson wraps JavaScript in a loving Ruby embrace. It embeds the Mozilla SpiderMonkey JavaScript runtime as a C extension.

The easiest way to freeze or travel through time in a Jasmine spec is to use the built-in jasmine.clock().

• After jasmine.clock().install() you can use it to control setTimeout and setInterval.
• Using jasmine.clock().mockDate() you can mock new Date() (which returns the current time in Javascript)

While you can use SinonJS Fake timers, using the built-in Jasmine clock will save you an extra dependency.

When you register a delegated event using on (or the deprecated delegate / live), it is somewhat hard to manually trigger these events manually, e.g. for testing.

After trying jQuery's trigger to no avail, I had success by using native Javascript methods to create and dispatch an event. For instance, to trigger a mousedown event:

element = $('...').get(0);
event = new MouseEvent('mousedown', { view: window, cancelable: true, bubbles: true }...

Chosen is a JavaScript plugin that makes long, unwieldy select boxes much more user-friendly. It is currently available in both jQuery and Prototype flavors.

Javascript that implements client-side hyphenation of HTML-Documents.

jQuery plugin to register callback functions to keyboard shortkuts. Keyboard events in vanilla Javascripts are super-painful to work with, so hopefully this library can help.

Added utility methods for the Prototype Javascript framework.

Prototip allows you to easily create both simple and complex tooltips using the Prototype javascript framework.

Please note: "Permission to use Prototip on your domain is required and can be obtained by paying a small fee."

String manipulation extensions for the Underscore.js javascript library.

Flot is a pure Javascript plotting library for jQuery. It produces graphical plots of arbitrary datasets on-the-fly client-side.

Javascript sprite library for Canvas

The Holy Grail of testing for front-end development; execute browser-less, console-based, javascript + DOM code right from within your Rails test suite.

PhantomJS is a minimalistic headless WebKit.

It has fast and native support for various web standards:

DOM handling, CSS selector, JSON, Canvas, and SVG.

PhantomJS can be fully scripted using JavaScript. It is an optimal solution for headless testing of web-based applications, site scraping, pages capture, SVG renderer, PDF converter and many other usages.

traits.js is a minimal, standards-compliant trait composition library for Javascript.

Compress and obfuscate Javascript code online completely free using this compressor.

JSMin is a filter which removes comments and unnecessary whitespace from JavaScript files. It typically reduces filesize by half, resulting in faster downloads. It also encourages a more expressive programming style because it eliminates the download cost of clean, literate self-documentation.

Sprockets is a Ruby library that preprocesses and concatenates JavaScript source files. It takes any number of source files and preprocesses them line-by-line in order to build a single concatenation. Specially formatted lines act as directives to the Sprockets preprocessor, telling it to require the contents of another file or library first or to provide a set of asset files (such as images or stylesheets) to the document root.

Highslide JS is an open source image, media and gallery viewer written in JavaScript.

Grafico is a javascript charting library built with Raphaël and Prototype.js. The library provides a wide array of graphs and stays with the guidelines laid out by Stephen Few and Edward Tufte. Grafico provides pretty charts that effectively communicate their information.